FAUNA OF THE AFRICAN LAKES. 



511 



teristic of the ocean were to be found, this would afford very 

 vahiable evidence concerning the ancient history of the lake. 



It was with this end in view that a Third Tanganyika Expe- 

 dition (68) was organised by the Committee, with the conduct of 

 which I had the honour of being entrusted. One of the principal 

 objects of this expedition was therefore to make a careful collec- 

 tion of the water plants of Tanganyika, at the same time 

 collecting in Nyasa, with the idea of atfordiug a comparison with 

 a more normal African fresh-water lake. My instructions also 

 provided " That other groups of organisms likely to throw light 

 on the Tanganyika Problem, and especially fishes, shall not be 

 neglected." Including observations on various points of interest, 

 the work before the expedition was thus sufficiently extensive, 

 although matters of geology and geogj'aphy were outside the field 

 of enquiry. 



I left England in the spring of 1904, proceeding via the 

 Zambezi and 8hirc rivers to Lake Nyasa, where a few weeks were 

 spent in collecting. My stay on and around Tanganyika lasted 

 about eight months, which w^ere fully occupied in making collec- 

 tions and observations as far as facilities offered. Returning to 

 the coast by w^ay of the Victoria Nyanza, an opportunity was 

 afforded of obtaining representatives of the flora of that lake for 

 purposes of comparison with the plants collected in Nyasa and 

 Tanganyika. 



It may at once be stated that the fioi-a. of Tanganyika fails to 

 exhibit quite the remarkalde features which some had expected 

 it to show. As regards the higher aquatic plants, a comparison 

 of the species from Tanganyika with those from Nyasa and 

 Victoria Nyanza does not throw any light on tlie hypothesis of a 

 marine origin for Tanganyika. The fresh- water A]gre of the 

 lake, however, have proved to be a strange and interesting 

 assembty, a considerable number being peculiar to Tanganyika 

 w^hile several show undoubted marine affinities. The lower forms 

 of vegetable life which occur thus tend to confirm the unique 

 biological nature of the lake. 



On the zoological side, my collections have added not a little 

 to the number of forms known from the lakes, the results 

 appearing as a sei'ies of memoirs principally in the Proceedings 

 of the Zoological Society. For the first time systematic tov/- 

 nettings were made in Tanganyika on a,n extensive scale, and as 

 a result, detailed information is to hand about whole gr<)Ui[)S of 

 organisms, only the Imre existence of which in the lake was 

 known before. Thus reports have now been published on the 

 smaller Crustacea, (Copepoda, and Ostracoda) as well as on the 

 Rotifera, while in addition the groups Rranchiura and Hydrach- 

 nida are new recoi-ds from the lake. 



In completing this brief review of the zoological exploration of 

 Tanganyika, it is oidy necessary to refer to the Ijelgian expe- 

 dition to that lake and to Lake Mwero undertaken by the late 

 Louis tStappers. This ex[)editi()n visited Tanganyika in 1912- 



